The interest in oxidizers which have unusually large surface areas results from the emergence, within recent years, of newer performance requirements, specified for advanced interceptor missiles. These performance requirements have required ultrahigh burning-rate propellants.
The efforts to meet the high performance requirements of ultrahigh burning-rate propellants have been concentrated mainly on the use of a combination of combustion catalyst (such as ferrocenyl or carboranyl derivatives) in conjunction with fine forms of oxidizer. High burning-rate composite-modified double-base propellants have also been developed by using fine oxidizer in conjunction with metallic fibers or staples.
Presently, ammonium perchlorate of high surface area, is manufactured by two processes. These processes relate to:
1. Ultrafine ammonium perchlorate, or submicron size that is manufactured by a grind process involving the use of a Vibroenergy mill.
2. Porous ammonium perchlorate that is produced by the thermal decomposition of ammonium perchlorate. This process can be carried out at 300.degree.-400.degree. F. until a weight loss of about 28% takes place.
Advantageous would be a process of manufacturing ultrahigh surface area ammonium perchlorate particles wherein the ammonium perchlorate which is removed during the pore forming procedure is recoverable and can be recycled, thereby resulting in a more economical process.
Also advantageous would be a manufacturing process for making porous ammonium perchlorate which has superior properties for promoting propellant burning rate and which can be used in place of ultrafine ammonium perchlorate, of either the small-micron or submicron size, prepared by a grinding process or porous ammonium perchlorate prepared by a thermal decomposition process.
An object of this invention is to provide a method of manufacture for solid oxidizers hving a very large surface area.
Another object of this invention is to provide a method of manufacture for solid oxidizers which method yields a product having superior properties for promoting propellant burning rate, a product which can be used in place of ultrafine oxidizer, of either the small micron particle size or submicron particle size prepared by a grinding process or porous oxidizer prepared by a thermal decomposition process.
A further object of the method of this invention is to employ an etching process in the pore forming procedure on and within the oxidizer paricles which process facilitates the recovery of the oxidizer which is dissolved by the selective extractants that are used to cause etching which results in the formation of indentations and/or cavities on the surfaces of the oxidizer particles and crevasses and tunnels in the oxidizer particles. The result of the etching process is a large increase in the surface area of the oxidizer particles.